Renowned virologist Shane Crotty, PhD joins us again to address the most important COVID-19 questions: Should people who’ve been vaccinated or had COVID-19 continue to wear masks and physically distance? How will each vaccine hold up to the SARS-CoV-2 variants? What does the research say about people who’ve already had COVID-19 who get a vaccine? How long will immunity last for the vaccines or COVID-19 infection?

Shane Crotty is a Professor at the La Jolla Institute for Immunology, Center for Infectious Disease and Vaccine Research, Crotty Lab. Prof. Crotty also has an academic appointment with the University of California San Diago. See his full bio here:
Prof. Crotty on Twitter:

Interviewer: Kyle Allred, Physician Assistant, Producer and Co-Founder of

(This video was recorded on March 23, 2021)

Just to clarify at 8:40 in the video: Prof. Crotty is describing a theoretical person when he says “I myself am comfortable getting infected…” He hasn’t had COVID, and doesn’t have that opinion. He was explaining one end of the spectrum of level of concern for individuals.


0:00 Intro
0:46 Heated exchange between Dr. Fauci and Senator Rand Paul
1:00 How long does immunity last for those who’ve had COVID-19?
3:31 How antibody levels and T cells drop over time
4:03 Dr. Fauci: Difference between in vitro and real-world studies
4:36 Population-based studies about COVID 19 immunity against reinfection
6:22 Huge variability from person to person for post coronavirus immunity
8:20 Policy decision: individual vs. community goals during a pandemic
9:03 Very rare for hospitalization from COVID-19 reinfection
9:34 Avoiding COVID-19 infection and transmission potential
10:12 Should mask-wearing continue for those who’ve had COVID-19?
12:23 If I’ve had COVID-19, shouldn’t my vaccine dose go to someone else?
13:39 Vaccines are eliciting more immunity than natural infection
14:02 Is natural immunity always better than a vaccine?
20:05 If you’ve had COVID-19, when should you get vaccinated? Both doses?
22:07 How are variants “game changers” for vaccines and natural infections?
24:53 Can’t I stop wearing masks and distancing after a vaccine or having COVID?
26:14 Variants of concern: B.1.1.7 (UK) and B.1.351 (S. Africa) details and implications
30:57 South Africa Variant escaping immunity: AstraZeneca Vaccine data
32:28 Isn’t preventing COVID 19 hospitalizations and deaths the primary goal?
35:25 Will we need updated coronavirus vaccines?
36:38 Johnson and Johnson vaccine versus the variants
37:57 Preventing transmission to prevent SARS CoV 2 mutation opportunities
38:40 Coronavirus antibodies vs T Cells and other parts of the immune system
39:54 Replication and asymptomatic spread of COVID-19 vs. Pneumonia
42:53 Vaccine incentives and Senator Rand Paul’s perspective
45:35 Looking ahead, SARS-CoV-2 vs Influenza, Will we need annual vaccinations?
52:20 Current research and goals for Prof. Shane Crotty



Crotty’s Research Published in Science |

Variant Tracker |

Denmark Research in the Lancet |

UK SIREN study:

Research from Qatar |

UK Research in NEJM |


Congressional Hearing 3/8/21: exchange with Dr. Fauci and Rand Paul: (PBS News Hour) and (CNBC)


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Video Produced by Kyle Allred


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#COVID19 #Coronavirus #COVID19UK


By earmpy

38 thoughts on “COVID Variants vs. Coronavirus Vaccines (AstraZeneca, Pfizer, Moderna, Johnson & Johnson) + Immunity”
  1. Here's an extra video clip with Professor Crotty's response to the question "Does a Positive Antibody Test = COVID 19 Immunity?"

    Thanks for watching and be sure to check out our other MedCram interviews with Shane Crotty: 
    – COVID 19 Vaccine Deep Dive: Safety, Immunity, RNA Production:
    – Coronavirus Mutations and COVID 19 Vaccine Implications:

  2. I wish he would define what he means by mask. There are many things people wear it’s just not clear what TYPE of mask and why. Are we talking N95s?

  3. Substantial protection not perfect protection that is the same as the injection. Overall most people have, it's plausible, no simple way to predict, most people have substantial immune memory, 5% maybe don't. The numbers of people reinfected and hospitalized is very low. All of this information is confirming that I will not be getting the vaccine.

  4. Seems like a nice guy, well-intentioned, earnest – but I would like to see something a bit more recent from him. This is already feeling dated and a pretty strong push for the V-cine.
    The issue of variants is extremely confusing. Some say that the variants are not all that different than the original and others say they are. And then there are opposing views as to the efficacy of the V-cine against them.

    The idea that he is suggesting of getting past this by vaccinations is running into a wall in my thinking. What about flu variants and the "need" to keep getting a new shot each year?

  5. Great interview. Prof. Crotty is one of the people on my short list of really rigorous scientists who are looking to get at the truth. Always a pleasure to hear him talk.

    One interesting exchange was around 14 minutes, where the question was asked about prioritizing individuals for the vaccine who haven’t had Covid. I found that to be the weakest answer because statistically speaking people without prior infection are at massively more risk of severe Covid. Thus, to save the most lives you would prioritize them for vaccine. No one is saying natural immunity is 100% bullet proof, but we are talking about prioritization here. Seems like Prof. Crotty is simply trying not to contradict the public health recommendations, but a scientist shouldn’t have to self-censor in such a way. By his own data, in order to minimize population wide harm, you have to prioritize the highest risk individuals.

  6. Interesting but he still talks like this is the plague and we all need a vaccine to survive!
    I cannot get on board with this assumption.

  7. If antibodies are better for vaccinated vs natural infection, why is the Red Cross not accepting convalescent blood plasma from the vaccinated to support those who need antibodies? They state the natural antibodies are higher than those from vaccinated. 

    This seems to go against your premise near the 15 minute mark that vaccinating for this virus is better than natural immunity.

  8. Why isnt there any discussion and comparison with sinovac? In indonesia, it is considered the best. compared to any other brand. Moderna is even avoided

  9. Exactly right. If you had Covid and recovered you already have NATURAL IMMUNITY. Your bodies immune system t cells have immune memory and natural antibodies.

  10. Excellent. We're now on 5/16/21. MedCram/Dr. Roger helped me going through COVID from the outbreak to pandemic. I'd love to find out about any data on the vaccinated Americans, Worldwide ppl., if any yet. I rely on Science not polititicians, media.
    As someone mentioned below, why the World, and the American ppl didn't had Dr. Crotty speaking, teaching, informing the World. It seems Scientists passed on their info to gov agencies and they provide the info that suits them. I dont know, but we shouldn't never have to be in the current situation.
    Last year, I shared all Dr. Seheault's videos on Tweeter and Face. It's understood that there are much more to be studied, researched, proven etc. Please keep on sharing and lighting the dark Covid road. So appreciate. Thank you. I'm still 0_o 😕

  11. Dr Seheult… There is a new study that says COVID 19 is not a respiratory condition; It is a VASCULAR. ! Could you please elaborate on that.? Talk about that… I want to hear your point of view,,, Your analysis of that study.. Thanks a lot
    We missing you. # weeks ago Nada de NADA.!!!

  12. Quercetin and Zinc ,C,D NAC is our protection. We still got it in December from my husbands work .fellow employees had it way worse ,to a point of ER
    visits, trouble breathing, dehydration. Where as my husband did not have it like them. I had a light version. We took Quercetin and Zinc through out our 14 days of sickness and quarantine. Which didn’t allow the virus to duplicate. Beyond that we have higher BMI,high blood pressure, over 50 me 60 in July plus I’m immune compromised. Should have been worse right, Quercetin also is preventative against other viruses. My info… med cram update 32,34 and 59. Thank you for your intel

  13. i was actually one of the first people to get the covid vaccine because i was in the vaccine trials. i got my first shot of the moderna vaccine in september and my next shot in October. im actually worried about how long the immunity last because it's been so long.

  14. Dr Shiva talked about many of these things at the beginning of the Covid 19 last year. The more information we get, it is more important. Thank you MedCam.

  15. For those medically unable to get a vaccine, is it possible to get a test to see if they might be immune anyway? How likely is that if at all? I'm really worried about this group and the possibility that their travel or daily activities will be limited.

  16. What are the possibility of Vaccines induced antibody facilitating Variance of Viruses, while having asymptomatic infection? Also about hyper-immune response?

  17. I trust Dr. Crotty more than my PCP and the CDC. 😁 Dr. Crotty, Dr. Dan et al paper is very illuminating. Currently, more published peer reviewed research studies (2021) supported longevity of antibodies of post-Covid infected individuals. Similarly, a very recent research paper (Nature Medicine 2021) found that individuals previously infected with COVID-19 developed vaccine-induced antibody responses after a single dose of the Pfizer-BioNTech mRNA vaccine that were similar to antibody responses seen after a two-dose vaccination course administered to infection-naive individuals.

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